"Giant Fireball" Impact in Peru Upends Meteorite Theory

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The question is how the meteor—which Schultz estimates to have been roughly the equivalent of a three- to six-foot-long (one- to two-meter-long) boulder—managed to stick together and retain its speed, rather than dispersing into a shotgun blast of small fragments.

In research presented today at the Lunar and Planetary Science Conference in League City, Texas, Schultz and colleagues suggested that the fragments might have been trapped and smoothed into an aerodynamic shape by the shock wave created by their movement through the atmosphere.

He compares it to the way sediments in a streambed can be shaped by flowing water.

"Rather than flying apart," he told National Geographic News, "[perhaps] it shaped into a needle and pierced the atmosphere."

(Related: "Asteroid Crash Sent "Meteorite Express" to Earth, Study Says" [July 14, 2004].)

Owen B. Toon, an atmospheric scientist at the University of Colorado at Boulder who was not involved in the study, finds it "quite interesting."

"We know from impacts such as Tunguska [a Russian fireball that flattened trees in a 1908 impact] that fairly large objects [half a football field in diameter] can blow up in the atmosphere and leave no crater or obvious debris field on the ground," he said by email.

"The behavior is related to the strength of the material, since iron objects of this size leave a large crater behind. Hopefully Peter [Schultz] will learn more about the crater and impactor in this [study] so that we can understand better how it reached the surface."

Kevin Zahnle, a meteorite researcher at NASA Ames Research Center, agrees.

"In part prior theory had overlooked the possibility of such impacts because all small craters on Earth whose impactors could be identified had been hit by iron or iron-containing meteorites," he said by email.

But "[s]imple theory suggest[s] that at least some of the little craters should have been made by stones, given that most of the meteors are stones."

Protection Needed

Regardless of what happened, Schultz wants to see the crater protected for future research.

Humans rarely see a meteorite landing, he said—for instance, "Meteor Crater [in Arizona] is 50,000 years old."

(See a photo of Meteor Crater.)

Furthermore, the Peruvian meteor's surprising arrival raises the question of how many more meteors may have crashed into Earth in a similar fashion.

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